Sitecake - Drag and drop CMS for HTML websites. It's flat file CMS so it's pretty fast.
Buy For Life - Find the most durable and sustainable products in the world
Anchor CMS - Free and lightweight blogging system
Greenlist - Start a sustainable company lifestyle, on Slack
Textpattern - Textpattern is an elegant content management system that is free, open source software.
Hempies - 100% organic, super sustainable toilet paper